I've tried to play rhythm to a metronome.
Set it for a speed and it goes click ... click ... click ... click ... Then you start to play, and you're consistant, because you're consistant. But the clicks, man! click ... ... click click ... click ... ... ... click ... It's horrible how metronomes click right on time, every time, until you try to play, then they're all over the place!
That's the denial talking. I know it's me that's wavering. But most of your music isn't you and a clicking sound under a microscope. Most of it's much less structured than that. I've mentioned but not gone into detail about time, but the suck needle turns up higher when you blow time than when you blow pitch. In a perfect world, you'd hit both, but in a perfect world, Richard Thompson would rule the pop charts and Britney Spears would be working in a chicken ranch outside Pahrump, Nevada. Well, one of those could happen.
What I used to do, back when MTV still played videos, is to sit and watch MTV and strum along, holding the strings mute. The point wasn't to play along, to figure out the keys and the like. That was far beyond me. The point was to learn rhythm.
And when you do this, it's best to listen to the drummer, not the guitars. In funk, the guitar closely aligns to the snare drum. It's good to think of a guitar wider than that, but I think of funky rhythms like the Amen break and try to do that, with the low strings being the kick drum and the treble strings being the snare or hi-hat. Amen or Funky Drummer won't always work. For Country, it's boom-chick, with boom being the big strings. But breaking the rhythm into smaller pieces always works. That's why musicians speed up, because going faster means the chunks of time are smaller.
In my regular gig, I'm the rhythm guy with inconsistent and regularly-cycling drummers. So, I'm the drummer's drummer, the guy he picks up the rhythm from. Pribek (link to the right) says being that guy, being Mister Strum, is the way out of a bad situation. If you want to not suck, get good at rhythm.